Chromatography is a widely used analytical technique for the chemical analysis and separation of molecules. Chromatography involves the separation of one or more analyte species from matrix components present in a sample. The analytes and matrix components have an affinity for the stationary phase. In ion exchange chromatography, the stationary phase includes ionic moieties that ideally will bind to the charged analytes with varying levels of affinity. An eluent is percolated through the stationary phase and competes with the analyte and any matrix components for binding to the ionic moieties. The eluent is a term used to describe a liquid or buffer solution that is pumped into a chromatography column. During this competition, the analyte and any matrix components will separate from each other by eluting off of the stationary phase as a function of time and then be subsequently detected at a detector. Examples of some typical detectors are a conductivity detector, a UV-VIS spectrophotometer, and a mass spectrometer.
Chromatography typically requires a calibration process to both identify the analyte of interest and quantitate the amount of analyte. A standard solution is often used as part of a calibration process for determining the chemical identity of the chromatographic peaks of a sample solution. The standard solution can have one or more types of analytes where each one is at a known predetermined concentration. A chromatogram of the standard solution will provide the retention times, peak heights, and peak areas for the analytes in the standard solution. Such information acquired with the standard solution can be compared to the chromatogram of a sample solution to determine the chemical identity and concentration of the components in the sample solution. For instance, the peak retention times of the standard solution can be correlated with the peak retention time of the sample solution to determine the chemical identity of the peaks of the sample chromatogram. The chemical identities of the standard components are verified by injecting individual pure components of the standard and these identities are established by the peak retention times.
In regards to quantitation, several dilutions of the standard solution can be prepared manually and analyzed chromatographically. It should be noted that user error can be significant when manually preparing diluted standard solutions. The measured peak areas or peak heights from the diluted standards can then be used to calculate calibration slopes and intercepts for each of the analytes in the standard solution. A sample containing one or more analytes can be analyzed chromatographically to measure one or more peak areas corresponding to analytes. These peak areas can be used to quantitate analyte concentrations based on the corresponding calibration slopes and intercepts. Applicant believes that there are several problems with calibration and sample analysis processes in that the process needs to be more automated in analyte identification, diluting standard solution for calibration with reduced user input, determining proper calibration concentration ranges, and automated sample concentration calculations.